Alesis Datadisk SQ MIDI Sequencer Sysex Data Storage
Update 02-13-2026
This is a practical tool in the studio and on stage. Before this was
available, cassette tapes were the only medium for storing MIDI
data. Tapes were unreliable and finicky to work with. The Datadisk
was the first rackmount MIDI storage device that used 3-1/2 inch 2DD
720KB floppy disks (hey it wasn't bad for 1987!). Sadly, since it
was discontinued no one has made a similar product that uses modern
RAM storage such as USB or SD. As a MIDI Sysex storage device, the
Datadisk can store MIDI sysex patch data from MIDI devices. The "SQ"
model adds realtime recording and playback of MIDI sequences without
using RAM buffers.
The 16x2 LCD display with the buttons makes the unit easy to
operate, although the backlight on the LCD fades with age. When you
save MIDI sysex data, it automatically names the received sysex dump
with the manufacturer name (although it is old enough that newer
makers may not be recognized). You can rename the patch names. 16
characters per line aren't a lot but it was better than none at all.
53 sysex files maximum can be stored on a floppy as long as the sum
of their sizes do not exceed the 800KB maximum of the disk. The MIDI
Out/Thru jack can function as an output or a "software THRU" jack
(AKA "MIDI Echo"). Patch data - such as sample data - can be sent
remotely while a sequencer is playing over a selected MIDI channel
using program change messages.
The sequencer system isn't meant to be any kind of editor; it
records MIDI data in real time with time stamp and plays them back.
Playback can be the same tempo as recorded or sync'd to MIDI clock.
The Datadisk responds to MIDI Start/Stop/Continue/SPP. I figured out
how to use my Alesis Andromeda as a clock for the sequencer, which
was great because I could program the clock setting with every MIX
used for each song. The Andromeda also has a feature where a
footswitch jack can be configured as a Start/Stop MIDI footswitch.
This allows me to play back sequences without a laptop or mobile - I
refuse to use them as I have seen too many laptops crash during a
performance. There is no reference in the user manual about MIDI
Time Code or MIDI Machine Control.
The format of the floppy disks are an Alesis proprietary format, so
the disks cannot be read from a generic computer. The Datadisk
implements the MMA Sample Dump standard, as long as the sending
device also implements it.
If you purchase one of these, be sure that it includes the "lump in
the middle" power pack. It needs to be the Alesis power pack that
provides 9VAC at 20VA into a DIN 4pin 240deg plug (these are used
for other Alesis products). My units are powered from my Juice Goose 12PAQ using
this wiring.
Gotek makes floppy drive emulators that have USB ports for USB
storage devices - the model SFRM72-TU100K is a compatible emulator
(3.5in 5VDC/4pin 34pin interface 2DD 720KB) for Datadisk models with
the Sony floppy drive. However, earlier Datadisk models used a
Fujitsu floppy drive that used 12VDC - I don't know if Gotek makes a
compatible emulator. To find out which one your unit has, you have
to remove the top and back panel, then remove the four small screws
under the floppy drive and look around the drive for a label that
identifies the OEM. The service manual also says that the two drives
use different mounting arrangements to the chassis, I do not know
how much of a difference they are.
These have been real handy utilities for MIDI patch storage, and the
original drives are still going strong after 30+ years. Although I
am not tempting fate and will be replacing the floppy drives with
emulators soon. Floppy disks don't last forever and it is highly
recommended that you create backup copies - I have had some floppies
fail. USB storage isn't 100% robust either, but they are much more
reliable and can hold more storage than the 720KB disks. By
including a Datadisk in the studio and another in my stage
rig, I can do offline sound design for songs in my band in the
studio, then transfer the MIDI data to the stage rig with a floppy
disk.
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